1. Field of the Invention
The present invention relates to an apparatus for preventing backlash of a transmission for a vehicle, and in particular, a new and useful bearing for preventing backlash of a transmission in which a gear is mounted on a driving shaft which can smoothly mesh with another gear mounted on a passive shaft.
2. Description of Background Art
In the past, backlash preventing bearings, such as a roller clutch, over running clutch or over running roller clutch, were used so that a transmission rotates in only one direction. The rotation of the transmission in the opposite direction cannot be achieved.
Therefore, in a gear assembly of which the driving shaft gear is fixed to mesh with the passive shaft gear, the bearing can properly prevent backlash of the transmission of the vehicle. However, when the passive shaft is not rotated, in the case when the passive shaft gear must be meshed with the driving shaft gear, the probability that the driving gear will properly mesh with the passive gear to be rotated as compared with the probability that the driving gear will not properly mesh with the passive gear to be rotated is approximately fifty percent.
That is, in the case where the passive gear being meshed with the driving gear is stopped, the teeth of the passive gear and the teeth of the driving gear are not meshed exactly with each other. Sometimes each gear is met with free ends of the teeth so that power cannot be transmitted from the driving gear to the passive gear.
The above problems are raised because there is no relative clearance for moving between the driving gear and the passive gear. No clearance between the gears cause the teeth of the gears to be exactly meshed or not exactly meshed according to the condition of the mating of the teeth.
Therefore, in the backlash preventing apparatus of the prior art constructed as above, it is difficult for the teeth of gears to be exactly meshed in the condition when the passive gear is stopped.